<VV> Greasing axle bearings

[Tony Underwood]

At 08:42 PM 3/20/2011, Clark Hartzel wrote:
>On a late model Corvair the rear axle hubs are similar to a front hub in
>that there are two bearings with a space between them.  It is possible to
>drill and tap a hole in the cast iron housing and pump grease in there.  Of
>course you will not know if the grease ever goes into the bearings until you
>see it oozing out of the seals and getting on your brake parts.


Agreed.   Been there done that.


>On an early Corvair the axle bearing is one assembly consisting of two sets
>of rollers and two outer races in a stamped steel housing.  The housing
>could be drilled for an oil hole but there is not enough thickness to screw
>a zerk fitting in there.  The other problem is the area between the rollers
>is covered by the A-arm flange so let me state this with great certainty:
>You cannot add a grease fitting to an early axle bearing.


Again, agreed.  Never tried being there or doing that because I don't 
see how you could do it.   There just isn't room.


>Now that I have said that, someone will surely pipe up to say they did it
>somehow!  I think the only hope would be sticking an insulin syringe thru
>the rubber seals and trying to squirt some grease in that way.


...or, doing it the way everybody has always done, slide the axle out 
and pop the bearing halves apart, clean and grease.


>I spent 37 years working for a machine tool company and talked many times to
>bearing engineers and sales reps.  They all say the same thing:
>1.  You should never take an old bearing off a shaft to regrease it and
>     press it back on.


The logic here is that once stretched, the bearing won't grab the 
shaft.  I tend to disagree, having done just that with good 
results.   And yes you CAN get a good idea of how tight the bearing 
is on the axle shaft by simply testing how much torque it takes to 
remove it in the first place and how much is required to press it 
back on again... then a 3rd test to see what's required before you 
can again move it.

If there's doubt, and the bearings grip on the axle is too loose to 
trust, you've lost nothing but your time.   And, there IS always the 
prior option of splitting it and clean/grease without removing it anyway.


>2.  You can't "rebuild" a bearing by taking several apart and using 
>the best pieces to make one good one.

Nope... but you can possibly refurbish one if there's adequate 
substance left to work with, like replacing a row of rollers that may 
have pits, with salvaged rollers from another bearing that had one 
row of its rollers fail, trashing half the inner race etc.

I know, lots of hassle... but if there's a stash of such parts on 
hand, and it's a rainy weekend afternoon and there's nothing much to do...




>3.  A bearing only needs a thin film of grease on the balls or rollers and
>     the races.

Yep.   And only a very thin film at that...


>The bearing will throw out the extra grease it doesn't need
>     and you should never fill up the space between bearings with grease.


This is why I'd mentioned blowing out excess grease with air so this 
doesn't happen.   There will be enough left on the contacting 
surfaces to keep the bearing happy.


>Clark Hartzel (with flame suit on)


...no flames from the likes of me,


tony..    remembering the excessive frugality of 'Vair owners